Beatty 17.1_ELECTROCHEM_(W1)_2023_Answers

1 Beatty Secondary School Science Department (Chemistry Unit) Chemistry 6092 Name: ___________________________________ ( ) Date: _______________ Class: 4E___ TOPIC: ELECTROCHEMISTRY (WORKSHEET 1) – ELECTRICAL CONDUCTION & ELECTROLYSIS OF MOLTEN COMPOUNDS Learning Objectives: (a) Describe electrolysis as the conduction of electricity by an ionic compound (an electrolyte), when molten or dissolved in water, leading to the decomposition of the electrolyte. (b) Describe electrolysis as evidence for the existence of ions which are held in a lattice when solid but which are free to move when molten or in solution. (c) Describe, in terms of the mobility of ions present and the electrode products, the electrolysis of molten sodium chloride, using inert electrodes. (d) Predict the likely products of the electrolysis of a molten binary compound. (e) Construct ionic equations for the reactions occurring at the electrodes during the electrolysis, given relevant information. Multiple-Choice Questions 1 When the experiment shown was set up, the bulb lit, but there were no decomposition products at the electrodes. What is X? A aqueous sodium chloride B bromine C molten sodium chloride D mercury ( D ) 2 Which substance, when added to water, makes a solution that is a good electrolyte? A calcium carbonate B copper C ethanol, C2H5OH D sodium hydroxide ( D )

2 3 The diagram shows apparatus used to investigate the conductivity of different solutions. Which substance, in aqueous solution of concentration 1 mol/dm 3, would cause the lamp to give the brightest light? A ammonia B ethanoic acid C ethanol, C2H5OH D sulfuric acid ( D ) 4 Two cells, P and Q, containing different liquids, w ere connected in the series with a battery, a suitable lamp and inert electrodes, as shown in a diagram. For which pair of liquids did the lamp light up? in P in Q A concentrated sodium chloride solution concentrated sugar solution B copper(II) sulfate solution propanol C ethanol molten lead(II) bromide D mercury dilute hydrochloric acid ( D ) 5 What are the products formed at the electrodes during electrolysis of molten magnesium chloride between carbon electrodes? positive electrode negative electrode A oxygen magnesium B magnesium chlorine C chlorine magnesium D chlorine hydrogen ( C )

3 6 Which pair of statements correctly describe the differences between the conduction of electricity during electrolysis and the conduction of electricity by metals? conduction during electrolysis conduction by metals 1 The current is due to the movement of both positive and negative ions The current is due to the movement of electrons. 2 Charged particles move towards both electrodes Charged particles move only in one direction only 3 It results in a chemical chang